The read and write head portions of the slider for use in a typical prior art magnetic disk recording system are built-up in layers using thin film processing techniques. Typically the read head is formed first, but the write head can also be fabricated first. The conventional write head is inductive and the read sensor is magnetoresistive. In the typical process of fabricating thin film magnetic transducers, a large number of transducers are formed simultaneously on a wafer. After the basic structures are formed the wafer is cut into rows or individual sliders. In a disk drive using perpendicular recording the recording head is designed to direct magnetic flux through the recording layer in a direction which is generally perpendicular to the plane of the disk. Typically the disk for perpendicular recording has a hard magnetic recording layer and a magnetically soft underlayer. During recording operations using a single-pole type head, magnetic flux is directed from the main pole of the recording head perpendicularly through the hard magnetic recording layer, then into the plane of the soft underlayer and back to the return pole in the recording head.
The shape of main pole piece at the ABS is critical for the performance of the write head. One approach of defining the main pole piece in a perpendicular head is to ion mill a laminated magnetic film using a hard mask, which is usually formed by milling through a layer of organic resist material such as Duramide using a photoresist mask. Due to the nature of ion milling, fencing is formed on the sidewall of remaining hard mask. Conventional stripping processes like wet strip or snow cleaning all have their disadvantages in removing the remaining hard mask. Wet stripping may not completely remove hard mask due to the fencing. This will make subsequent trailing shield fabrication process impossible due to plating etch problems from incomplete seed deposition over the fencing. On the other hand, snow cleaning could easily bow the critical pole piece shape. A CMP assisted lift-off process used in the prior art can effectively remove fencing but it can also lift off the hard mask. Therefore, an alumina refilling step is used after ion milling has been completed and before the CMP liftoff. CMP will polish off the higher topography areas, which usually is the stack of resist with refill material on top. However, very commonly, after the higher topography is removed, the pole underneath the hard mask, is damaged or rounded since nearby alumina is removed by CMP slurry.
What is needed is an improved method of fabricating the main pole piece structure for the write head.